Cellular Respiration

Transcription

1 Cellular Respiration

2 INTRODUCTION TO CELLULAR RESPIRATION Nearly all the cells in our body break down sugars for ATP production Most cells of most organisms harvest energy aerobically The aerobic harvesting of energy from sugar is called cellular respiration Cellular respiration yields CO 2, H 2 O, and a large amount of ATP

4 Glycolysis There are two important ways a cell can harvest energy from food: fermentation and cellular respiration. Both start with the same first step: the process of glycolysis which is the breakdown or splitting of glucose (6 carbons) into two 3-carbon molecules called pyruvic acid (pyruvate) The energy from other sugars, such as fructose, is also harvested using this process. Glycolysis is probably the oldest known way of producing ATP..

5 Glycolysis Cont d There is evidence that the process of glycolysis predates the existence of O 2 in the Earth s atmosphere and organelles in cells: Glycolysis does not need oxygen as part of any of its chemical reactions. It serves as a first step in a variety of both aerobic and anaerobic energy-harvesting reactions. Glycolysis happens in the cytoplasm of cells, not in some specialized organelle. Glycolysis is the one metabolic pathway found in all living organisms.

6 Summary Of Glycolysis Summary of the steps of Glycolysis: a. 2 ATP added to glucose (6C) to energize it. b. Glucose split to 2 PGAL (3C). (PGAL = phosphoglyceraldehyde) c. H+ and e- (e- = electron) taken from each PGAL & given to make 2 NADH. d. NADH is energy and e- carrier. e. Each PGAL rearranged into pyruvate (3C), with energy transferred to make 4 ATP (substrate phosphorylation). f. Although glycolysis makes 4 ATP, the net ATP production by this step is 2 ATP (because 2 ATP were used to start glycolysis). The 2 net ATP are available for cell use. g. If oxygen is available to the cell, the pyruvate will move into the mitochondria & aerobic respiration will begin.

9 Fermentation If no oxygen is available to the cell (anaerobic), the pyruvate will be fermented by addition of 2 H from the NADH (to alcohol + CO 2 in yeast or lactic acid in muscle cells). This changes NADH back to NAD+ so it is available for step c above. This keeps glycolysis going! In fermentation these pyruvic acid molecules are turned into some waste product, and a little bit of energy (only two ATP molecules per molecule of glucose actually four are produced in glycolysis, but two are used up) is produced. Out of many possible types of fermentation processes, two of the most common types are lactic acid fermentation and alcohol fermentation.

10 Lactic Acid Fermentation Lactic acid fermentation is done by some fungi, some bacteria like the Lactobacillus acidophilus. in yogurt, and sometimes by our muscles. Normally our muscles do cellular respiration like the rest of our bodies, using O2 supplied by our lungs and blood. However, under greater exertion when the oxygen supplied by the lungs and blood system can t get there fast enough to keep up with the muscles needs, our muscles can switch over and do lactic acid fermentation. In the process of lactic acid fermentation, the 3-carbon pyruvic acid molecules are turned into lactic acid. It is the presence of lactic acid in yogurt that gives it its sour taste, and it is the presence of lactic acid in our muscles the morning after that makes them so sore. Once our muscles form lactic acid, they can t do anything else with it, so until it is gradually washed away by the blood stream and carried to the liver (which is able to get rid of it), our over-exerted muscles feel stiff and sore even if they haven t been physically injured.

11 Lactic Acid Fermentation

12 Alcohol Fermentation Alcohol fermentation is done by yeast and some kinds of bacteria. The waste products of this process are ethanol and carbon dioxide (CO2). Humans have long taken advantage of this process in making bread, beer, and wine. In bread making, it is the CO2 which forms and is trapped between the gluten (a long protein in wheat) molecules that causes the bread to rise, and the ethanol (often abbreviated as EtOH)evaporating that gives it its wonderful smell while baking.

13 Alcohol Fermentation

14 Cellular Respiration An analogy can be drawn between the process of cellular respiration in our cells and a car. The mitochondria are the engines of our cells where sugar is burned for fuel and the exhaust is CO2 and H2O. Note that in a car that burned fuel perfectly, the only exhaust should theoretically be CO2 and H2O also.

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16 Cellular Respiration There are three steps in the process of cellular respiration: glycolysis, the Krebs cycle, and the electron transport chain. Occurs in the mitochondria Pyruvic acid from glycolysis diffuses into matrix of mitochondria & reacts with coenzyme A to for acetyl-coa (2- carbon compound) CO2 and NADH are also produced

24 Most cells produce molecules of ATP per glucose (66% efficient) Actual number of ATP's produced by aerobic respiration varies among cells

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26 ATP (Adenosine triphosphate ) Energy carrying molecule used by cells to fuel their cellular processes ATP is composed of an adenine base, ribose sugar, & 3 phosphate (PO4) groups The PO4 bonds are high-energy bonds that require energy to be made & release energy when broken ATP is made & used continuously by cells Every minute all of an organism's ATP is recycled Phosphorylation refers to the chemical reactions that make ATP by adding Pi to ADP ADP + Pi + energy «ATP + H2O Enzymes (ATP synthetase& ATPase) help break & reform these high energy PO4 bonds in a process called substrate-level phosphorylation When the high-energy phosphate bond is broken, it releases energy, a free phosphate group, & adenosine diphosphate (ADP)

MULTIPLE CHOICE: Circle ALL that are TRUE. There may be MORE THAN one correct answer. is the first step in cellular respiration that begins releasing energy stored in glucose. A. Alcoholic fermentation

Chapter 6 How Cells Harvest Chemical Energy Standard 1.g. Cellular Respiration Is the main way that chemical energy is harvested from food and converted to ATP Is an aerobic process Yields The Relationship

Cellular Energy In order to sustain life (steady state), cells constantly expend energy in the form of ATP hydrolysis the hydrolysis of ATP yields a molecule of ADP (adenosine diphosphate) and a Phosphate

Energetics... Page 18 Respiration Syllabus : The importance of respiration in converting chemical energy in food to chemical energy in ATP. The sites of respiration the sites of the various biochemical

Cellular respiration So why do we breathe? The big picture Heterotrophs cannot make their own food to supply their energy needs Instead they break down food to use the chemical energy stored in organic

5.3 Cellular Respiration Releases Energy from Organic Compounds In this section, you will distinguish among aerobic respiration, anaerobic respiration, and fermentation explain how carbohydrates are oxidized

Transfers of electrons during chemical reactions (oxidation-reduction reactions) Relocation of electrons in food molecules releases energy which can be used to synthesize ATP ATP is used to do ALL types

Chapter 7 How Cells Release Chemical energy Overview of Carbohydrate Breakdown Pathway Plants and all other photoautotrophs get energy from the sun, heterotrophs get by eating plants and one another ATP

How is a Marathoner Different from a Sprinter? Long-distance runners have many slow fibers in their muscles Slow fibers break down glucose aerobically (using oxygen) for ATP production These muscle cells

Cellular Respiration Page 9 I. The Importance of Food A. Food provides living things with the chemical building blocks they need to grow and reproduce. B. Food serves as a source of for the cells of the

Chapter 9 CELLULAR RESPIRATION HARVESTING FREE ENERGY Photosynthesis takes free energy and puts it into carbohydrates/sugars Carbohydrates can be stored for later use; light can not and neither can ATP

1 of 37 9-2 The Krebs Cycle and Oxygen is required for the final steps of cellular respiration. Because the pathways of cellular respiration require oxygen, they are aerobic. 2 of 37 The Krebs Cycle The

Chapter 7 Harvesting Energy: Glycolysis and Cellular Respiration Including some materials from lectures by Gregory Ahearn University of North Florida Ammended by John Crocker Copyright 2009 Pearson Education,

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Introduction Chapter 6 In eukaryotes, cellular respiration harvests energy from food, yields large amounts of, and Uses to drive cellular work. A similar process takes place in many prokaryotic organisms.

Lecture 12-13 Chapter 6 Cellular Respiration How do marathon runners and sprinters differ? Long-distance runners have many SLOW FIBERS in their muscles Slow fibers break down glucose for ATP production

Name Period Chapter 9: Cellular Respiration: Harvesting Chemical Energy Overview: Before getting involved with the details of cellular respiration and photosynthesis, take a second to look at the big picture.

1. An autotroph is an organism that a. extracts energy from organic sources b. converts energy from sunlight into chemical energy c. relies on the energy produced by other organisms as an energy source

Introduction to Biology Respiration Chapter 5 Introduction Being alive is work. Cells organize small organic molecules into polymers such as the proteins, carbohydrates, and so forth you studied last week.

Section: 3.4 Name: Opening Activity: What is the equation for photosynthesis? Latin Root Word: Review of Old Information: Review of Old Information: 1. All energy begins as what type of energy and from

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: Harvesting Chemical Energy Name Period Overview: Before getting involved with the details of cellular respiration and photosynthesis, take a second to look at the big picture. Photosynthesis and cellular

How Cells Release Chemical Energy Cellular Respiration Overview of Carbohydrate Breakdown Pathways Photoautotrophs make ATP during photosynthesis and use it to synthesize glucose and other carbohydrates

Cellular Respiration Cellular Respiration Have you ever wondered why exactly you need to breathe? What happens when you stop breathing? Cellular respiration is the set of the metabolic reactions and processes

Photosynthesis takes place in three stages: Light-dependent reactions Light-independent reactions The Calvin cycle 1. Capturing energy from sunlight 2. Using energy to make ATP and NADPH 3. Using ATP and

1. Glycolysis leads to the production of and two molecules of ATP. In the absence of oxygen, fermentation leads to the production of. Glycolysis plus the citric acid cycle can convert the carbons of glucose

Energy flows into an ecosystem as sunlight and leaves as heat Photosynthesis makes O 2 and organic molecules (like sugars and proteins), which are used in cellular respiration Cells use chemical energy

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Chapter 9: Cellular Respiration: Harvesting Chemical Energy Name Period Overview: Before getting involved with the details of cellular respiration and photosynthesis, take a second to look at the big picture.

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AP * BIOLOGY CELLULAR RESPIRATION Teacher Packet AP* is a trademark of the College Entrance Examination Board. The College Entrance Examination Board was not involved in the production of this material.

THE CITRIC ACID CYCLE Introduction In this Cbse Biology Notes on the Citric Acid Cycle, also called the Krebs Cycle, we will pick up where we left off in the last section with the aerobic product of glycolysis,

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